Daily temperature extremes over Egypt: Spatial patterns, temporal trends, and driving forces

Kenawy, Ahmed El; López‐Moreno, J. I.; McCabe, Matthew F.; Robaa, S. M.; Domínguez‐Castro, Fernando; Peña-Gallardo, Marina; Trigo, Ricardo M.; Hereher, Mohamed E.; Al‐Awadhi, Talal; Vicente‐Serrano, Sergio M.

doi:10.1016/j.atmosres.2019.04.030

Cited by 46 publications

(30 citation statements)

References 110 publications

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“…The annual average minimum and maximum temperatures are 15.8 • C and 24.6 • C, respectively. The summer maximum temperature commonly exceeds 30 • C, with frequent heat waves that may exceed 45 • C [18]. The winter minimum temperatures infrequently fall below 10 • C. Apart from agricultural land in the delta and close to Nile Valley, Egypt is characterized by a lack of vegetation activity with normalized difference vegetation index (NDVI) values, a proxy for green vegetation, generally close to zero [55,56].…”

Section: Study Areamentioning

confidence: 99%

“…Meteorological data were provided by the Egyptian Meteorological Authority (EMA) and subjected to a rigorous procedure to check data quality and homogeneity. A detailed description of this procedure is outlined in [18]. As illustrated in Figure 1, the spatial distribution of the meteorological observatories is generally uneven, as most of the stations are located in the delta, along the Nile Valley, and close to the Mediterranean and the Red Sea.…”

Section: Observational Datamentioning

confidence: 99%

“…2019, 11, 2369 3 of 29 modeling, natural hazards assessment and forecasting, etc.). One example is [18], the authors of which recently assessed changes in daily temperature extremes over Egypt during the past four decades . Overall, an inspection of these studies highlights the current limitations of meteorological records in Egypt either spatially or temporarily.…”

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confidence: 99%

“…These challenges strongly constrain any attempts for a reliable diagnosis of climate change and variability and their possible impacts in the country.With the current advancement in Earth observation in general and thermal remote sensing in particular, data retrieved from many sensors have been made freely available for research community, including, for example, the Advanced Very-High-Resolution Radiometer (AVHRR), Moderate-Resolution Imaging Spectroradiometer (MODIS), Spinning Enhanced Visible and Infra-Red Imager (SEVIRI), Meteosat Visible and Infrared Imager (MVIRI), Landsat 4 and 5 TM, Landsat 7 ETM+, Landsat 8 TIRS, Sentinel 2 and 3, and VIIRS. The space-based meteorological data are generally quasi-global, with high spatial and temporal resolution, opening interesting possibilities to overcome the current limitations of ground meteorological measurements [18][19][20]. Amongst the different platforms, the MODIS was launched in 1999 on board the Terra satellite and in 2002 on board the Aqua, representing a new avenue to sense the Earth's terrain, ocean, and the atmosphere.…”

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confidence: 99%

“…This assessment is important to identify and attribute the agreements/discrepancies between satellite and ground meteorological information, providing feedback to the climate modeling community and other users on the possible sources of these differences. Recently, a wide range of studies have focused on assessing the quality of satellite estimates of different climatic variables, including precipitation (e.g., [18,44,45]), cloudiness (e.g., [46,47]), surface temperature (e.g., [22,25]), soil moisture (e.g., [48,49]), and snow cover (e.g., [50,51]).…”

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confidence: 99%

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An Assessment of the Accuracy of MODIS Land Surface Temperature over Egypt Using Ground-Based Measurements

2019

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Space-based data have provided important advances in understanding climate systems and processes in arid and semi-arid regions, which are hot-spot regions in terms of climate change and variability. This study assessed the performance of land surface temperatures (LSTs), retrieved from the Moderate-Resolution Imaging Spectroradiometer (MODIS) Aqua platform, over Egypt. Eight-day composites of daytime and nighttime LST data were aggregated and validated against near-surface seasonal and annual observational maximum and minimum air temperatures using data from 34 meteorological stations spanning the period from July 2002 to June 2015. A variety of accuracy metrics were employed to evaluate the performance of LST, including the bias, normalized root-mean-square error (nRMSE), Yule–Kendall (YK) skewness measure, and Spearman’s rho coefficient. The ability of LST to reproduce the seasonal cycle, anomalies, temporal variability, and the distribution of warm and cold tails of observational temperatures was also evaluated. Overall, the results indicate better performance of the nighttime LSTs compared to the daytime LSTs. Specifically, while nighttime LST tended to underestimate the minimum air temperature during winter, spring, and autumn on the order of −1.3, −1.2, and −1.4 °C, respectively, daytime LST markedly overestimated the maximum air temperature in all seasons, with values mostly above 5 °C. Importantly, the results indicate that the performance of LST over Egypt varies considerably as a function of season, lithology, and land use. LST performs better during transitional seasons (i.e., spring and autumn) compared to solstices (i.e., winter and summer). The varying interactions and feedbacks between the land surface and the atmosphere, especially the differences between sensible and latent heat fluxes, contribute largely to these seasonal variations. Spatially, LST performs better in areas with sandstone formations and quaternary sediments and, conversely, shows lower accuracy in regions with limestone, igneous, and metamorphic rocks. This behavior can be expected in hybrid arid and semi-arid regions like Egypt, where bare rocks contribute to the majority of the Egyptian territory, with a lack of vegetation cover. The low surface albedo of igneous and limestone rocks may explain the remarkable overestimation of daytime temperature in these regions, compared to the bright formations of higher surface albedo (i.e., sandy deserts and quaternary rocks). Overall, recalling the limited coverage of meteorological stations in Egypt, this study demonstrates that LST obtained from the MODIS product can be trustworthily employed as a surrogate for or a supplementary source to near-surface measurements, particularly for minimum air temperature. On the other hand, some bias correction techniques should be applied to daytime LSTs. In general, the fine space-based climatic information provided by MODIS LST can be used for a detailed spatial assessment of climate variability in Egypt, with important applications in several disciplines such as water resource management, hydrological modeling, agricultural management and planning, urban climate, biodiversity, and energy consumption, amongst others. Also, this study can contribute to a better understanding of the applications of remote sensing technology in assessing climatic feedbacks and interactions in arid and semi-arid regions, opening new avenues for developing innovative algorithms and applications specifically addressing issues related to these regions.

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Section: Study Areamentioning

confidence: 99%

Section: Observational Datamentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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An Assessment of the Accuracy of MODIS Land Surface Temperature over Egypt Using Ground-Based Measurements

2019

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Recent Observed Changes in Extreme High‐Temperature Events and Associated Meteorological Conditions over Africa

Iyakaremye

Zeng

Ullah

et al. 2022

Intl Journal of Climatology

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More frequent and intensified high-temperature extremes are acceptable indicators of global warming, which pose serious socio-economic impacts. In the present research, the Climate Prediction Center daily minimum and maximum temperature are used to characterize high temperatures into intensity of hot days (TXx), hot nights (TNx), and frequency indices based on the 90th percentile of hot days (TX90p) and hot nights (TN90p) as defined by the Expert Team on Climate Change Detection and Indices from 1981 to 2020 over Africa. The regression approach based on iterative reweighted least squares and correlation analyses are used to estimate the trends in extreme high-temperature events and their relationship with various meteorological variables. Furthermore, the Pruned exact linear time algorithm is used to assess if the maximum temperature experienced an abrupt change. Results show that many parts of Africa experienced more frequent and intensified hot days and nights in the current period (1998-2020) compared to the recent past (1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997), suggesting a clear shift in climate. Thus, we used the climatological mean differences between meteorological parameters before and after the breakpoint to assess the relationship between atmospheric conditions and extreme high-temperature events. As a result, we found that the current period observed an increase in the geopotential height at 500 hPa and reduced total cloud cover, as well as an increase in upward longwave radiation resulting in an upsurge in the frequency of hot days over many African sub-regions. The present study's findings provide useful information for future planning and development of early warning systems to cope with risks associated with hot extremes.

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Variations in the probability distribution function of air temperature anomalies in winter and summer from 1961 to 2016 over China

Tian

Gong³

et al. 2021

Intl Journal of Climatology

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The rising of near-surface air temperature is the most obvious manifestation of global warming. The analysis of the probability distribution function (PDF) of temperature can deep our understanding of the current characteristics of climate and extreme temperature changes. In this study, the daily maximum, minimum and mean temperature observations from meteorological stations are analysed to construct the temperature anomaly PDF during 1961-2016 over China. The skewness and kurtosis of the PDF are compared between the 1961-1990 and 1991-2016 periods. The non-Gaussian tails of the PDF are also identified to qualify the deviation of the temperature probability density curve. The results show that near-surface air temperature in China increased during the recent decades. The daily minimum temperature increased more than the daily maximum temperature did, while the temperature increase in winter was larger than that in summer. The largest increase detected was 1.29 C for the daily minimum temperature in winter, contrasting with the smallest increase of 0.51 C recorded for the daily minimum temperature in summer between the two study periods. The temperature anomaly PDF generally presented a positive skewness in winter and a slightly negative skewness in summer. Obvious non-Gaussian tails in the temperature anomaly PDF were present in the majority of the study sites. Most areas showed a short cold tail in winter (except for southwestern China), and long cold tails were mainly observed in summer. These results can improve our understanding of the variation of extreme temperatures, and of the responses to global warming.

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Daily temperature extremes over Egypt: Spatial patterns, temporal trends, and driving forces

Cited by 46 publications

References 110 publications

An Assessment of the Accuracy of MODIS Land Surface Temperature over Egypt Using Ground-Based Measurements

An Assessment of the Accuracy of MODIS Land Surface Temperature over Egypt Using Ground-Based Measurements

Recent Observed Changes in Extreme High‐Temperature Events and Associated Meteorological Conditions over Africa

Variations in the probability distribution function of air temperature anomalies in winter and summer from 1961 to 2016 over China

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